The overall objective of this proposal is to continue the support at Vanderbilt University of an existing interdepartmental, multidisciplinary Population Research Center. The continuous support of the Center will maintain the efficiency of many population related projects now active at Vanderbilt and will permit development in new areas not presently represented at Vanderbilt. The research objectives of the Center include investigations on male reproductive physiology (sperm production, sperm biochemistry, sperm metabolism, sperm maturation, sperm capacitation, and development of male contraception), on female reproductive physiology (fertilization, cell division and implantation), and on reproductive endocrinology (mechanism of sex hormone action, pituitary hormones, and prostaglandins). Support is requested for an administrative core unit and 11 core facilities (Histology, Steroid Analysis, Electron Microscopy, Hormone Receptor, Tissue Culture, Organic Chemistry, Cyclic Nucleotides, Gonadotrophin, Immunology, Prostaglandins-Lipids, and Pharmacology). Support is requested for the development of three research programs--one on sperm metabolism, one on hormonally-induced growth and differentiation, and one on morphological correlates of male reproductive function. BIBLIOGRAPHIC REFERENCES: Danzo, B.J., Orgebin-Crist, M.-C., and Eller, B.C. "Androgen Regulation of Epididymal Function." In: The Biology of Spermatozoa (E.S.E. Hafez and C.G. Thibault, Eds.), Karger, Basel, p. 17, 1975. Danzo, B.J., Orgebin-Crist, M.-C., and Eller, B.C. "Changes in 5 alpha-Dihydrotestosterone Binding to Epididymal Cytosol During Sexual Maturation in Rabbits: Correlation with Morphological Changes in the Testis and Epididymis." Molec. Cell. Endocr. 3, 203, 1975.